.30 carbine crimp question

hey guys,

got a quick question on .30 carbine crimping, so i thought i'd send it over to you guys!

using a dillon 550b with 3-stage RCBS carbide dies, i'm currently guessing at how much crimp i should apply. also, after the cases go through the first 3 stages (including full-length sizing), when the crimp is applied, the case kind of "bulges" around the bullet slightly. Is this "bulging" normal for .30 carbine?

OAL is at 1.680", and case OAL is between 1.280" and 1.285". both cases in pictures 001 and 002 are bulging, but the right casing in both pictures bulges more than the left (the right casing having more crimp applied then the left casing).

Also: depending on how much crimp I apply depends on if there's a gap between the bullet and the mouth of the case. not sure which one is correct amount of crimp.

in pictures 003 and 004, the "gap" case is on the left, and the "no-gap" is on the right. in my first 100rnds ever loaded, i believed they looked like the left-side "gap" case (with no signs of overpressure on the fired cases). the gap is approximately 0.001", and the bullet is firmly seated.

components are Sierra 110gr FMJ bullets, sitting on 1 S&B and 1 Aguila casing.

any suggestions on how to proceed?

http://i240.photobucket.com/albums/f...30carb_001.jpg
http://i240.photobucket.com/albums/f...30carb_002.jpg
http://i240.photobucket.com/albums/f...30carb_003.jpg
http://i240.photobucket.com/albums/f...30carb_004.jpg

Thanks!

The buldge is normal... as for your 'gap' you want to remove the belling completely... so your 2nd pic shows the correct crimp.

Just because you have carbide dies,,you still need lube !!,,only straight wall brass requires no lube..not using lube will result in head seperation,,speaking from experience

thanks for the responses, guys

highpowershooter: i'll definitely go with the crimp used on the right casing, then. thanks for the advice!

Litt'le Lee: i most certainly still use lube when sizing the cases. i use the dillon spray lube, lube up a bunch of cases, and every second or third casing put into the dies is a lubed case.

Quote:

---

Originally Posted by macgunner01

thanks for the responses, guys

highpowershooter: i'll definitely go with the crimp used on the right casing, then. thanks for the advice!

Litt'le Lee: i most certainly still use lube when sizing the cases. i use the dillon spray lube, lube up a bunch of cases, and every second or third casing put into the dies is a lubed case.

---

You really need to quit crimping the case mouths. The >30 Carbine headspaces on the case mouth and absolutely no crimp is required. If you do anything simple taper crimp to straighten and remove the case mouth flare. You are asking for some serious misfires in eithe and M1 Carbine or a Ruger BH.

Also the bulge below the base of the bullet is caused because the case is sized too much. It is called the "coke bottle effect". If you don't want it then simple back out the FL carbide die a little at a time until it goes away.

Larry Gibson

Thank you for your reply, Larry! :)

Quote:

---

Originally Posted by Larry Gibson

You really need to quit crimping the case mouths. The >30 Carbine headspaces on the case mouth and absolutely no crimp is required. If you do anything simple taper crimp to straighten and remove the case mouth flare. You are asking for some serious misfires in eithe and M1 Carbine or a Ruger BH.

---

I definitely know about not crimping the bullet into place. My only question was how much of a taper is sufficient (because of explicitly not wanting to apply too much taper). The RCBS dies have a taper crimp die, and the most I'd ever apply is just to straighten the case belling.

Quote:

---

Originally Posted by Larry Gibson

Also the bulge below the base of the bullet is caused because the case is sized too much. It is called the "coke bottle effect". If you don't want it then simple back out the FL carbide die a little at a time until it goes away.

Larry Gibson

---

That is a great piece of info to know! I will definitely keep that in mind! A case suffering from the "coke bottle effect" is still safe to shoot though, correct?

Quote:

---

Originally Posted by macgunner01

A case suffering from the "coke bottle effect" is still safe to shoot though, correct?

---

Correct.

Don

Buy a box of Winchester or Remington or Federal or MagTech, or etc. .30 Carbine ammo. Measure the case mouth diameter of their loaded ammo. Produce yours to the same dimension.

thanks Duke and USSR for the info! it is greatly appreciated!

i thank you guys for all the helpful hints! i loaded up a test batch of 50, using Sierra 110gr FMJ Bullets sitting on top of Win-296 and Remington 7 1/2's.

All brass was trimmed to COL between 1.280 and 1.285. OAL was between 1.6785 and 1.6810. Are those sizes ok?

Quote:

---

Originally Posted by macgunner01

OAL was between 1.6785 and 1.6810. Are those sizes ok?

---

I ran into feed problems when I seated to an OAL of 1.680". I now make sure that my OAL is no more than 1.670".

Don

OAL is controlled by the mag on the carbine, not by the chamber throat.

Quote:

---

Originally Posted by jimb16

OAL is controlled by the mag on the carbine, not by the chamber throat.

---

Mine is controlled by the throat.

Don

The bullets you are using must be a short ogive form if you are running into that situation.

https://www.milsurps.com/images/impo...nebullet-1.jpg

Don

One day, I'll cast bullets. For now, it's Sierras for me. :)

Do you guys think I'll be ok using an OAL between 1.6785 and 1.6810? Or will I experience pressure spikes with the shorter rounds?

Ok, you are hitting the front band! Size? Should be .308-.309....I'm surprised the they aren't just engraving. How hard are they?
MNac, I'd go with the longest that feeds from your mag and chambers easily. Try putting a bullet into a lightly sized cast and chamberin the round. The throat/rifling should push the bullet back into the case. Carefully remove the case and measure the OAL. If it exceeds the OAL needed for proper feeding from the mag, go with the mag length. Otherwise, back the OAL a couple thousandths and go with that.

Really good advice and procedure so far for getting it right. Excessive OAL = won't enter and/stack in mag to start with. It does seem that the front band is the culprit so making sure that it is .309 is important. Normally deeper seating does effect the pressure; that would be critical in 9mm or other pistol cartridges, but it/a slight amount won't make too much difference in the 30 Carb. It does however have some relationship to the burning rate of the powder that you use. Faster powder is more sensitive. In the Ruger 30 carb Blackhawk I had to hide all of the front band (RCBS 120 grain mold) and reduce the charge accordingly as the front band+the long nose made the rounds too long and they tied up cylinder rotation on the recoil plate. JC

Quote:

---

Originally Posted by jimb16

Ok, you are hitting the front band! Size? Should be .308-.309....I'm surprised the they aren't just engraving. How hard are they?

---

Yeah, probably is the front driving band. They are just fine at 1.670", so no problem. Cast bullets for rifles are handled a bit different than handguns. Whereas handgun bullets are usually sized to .001" over bore size, accurate loads for rifles are typically found at .002" or more over bore size. I cast mine at a 3/1 linotype/WW ratio and size them to .310".

Don

Just for the record, carbine barrels are supposed to be .3075 not .308. So .309 would be .0015 ove nominal bore diameter. I size mine to .309 and get good accuracy. I can see where .310 in a slightly worn barrel would work just fine.